This invention relates generally to the machine tool arts. More particularly, the present invention relates to a portable tool that may be secured to a workpiece for enlarging the bore thereof.
The utility of the present invention may best be appreciated in an environment such as plastic valves, fixtures, fittings, etc. wherein it is necessary to remove lengths of pipe which are frequently adhesively secured therein. It should be particularly noted, however, that the present invention is not so limited and this particular environment is used for purposes of illustration only.
There are many examples of prior art structure that are directed generally to the basic function as the present invention. For example, it is frequently necessary to recondition the bore of a cylinder in an engine in order to remove ridges formed by piston wear. One example of just such a device is disclosed in U.S. Pat. No. 2,304,405 granted on Dec. 8, 1942, to E. D. Green. In the Green patent, there is disclosed structure which includes means that are to be mounted on the cylinder such that the cutting tool may enter the cylinder. The cutting tool is mounted in a housing and is adjustably positionable by means of an eccentric arrangement so that when the teeth of the cutting tool and a pair of guide means contact the side wall, the ridges formed by piston wear can be removed. The pair of guide means are normally positioned below the ridge that is to be removed in order to prevent further cutting when the proper quantity of material has been cut. Vertical adjustment of the cutting tool is also provided in the Green patent.
While the Green patent does permit eccentric adjustment of the cutting tool, there is no disclosure of a pivotal handle for carrying the cutting tool, nor is there any disclosure of a plate that rotates relative to a clamp that is secured to the workpiece for guiding the cutting tool concentrically with respect to the bore of the workpiece. It should be further noted that it is relatively difficult to adjust for a change in depth of cut in a radial direction with the structure disclosed by Green. Still another shortcoming of the Green device is that provisions are not made that will permit adaptation of the tool to cylinders having different outside diameters.
Another form of prior art structure is disclosed in U.S. Pat. No. 2,917,976 granted on Dec. 22, 1959, to E. G. Stovall et al. The patent granted to Stovall et al. may be considered to be in the same general field to which the present invention is directed in that Stovall et al. teach structure for bevelling the end of a pipe. The Stovall et al. structure provides a constant bevel on the pipe end even when the pipe is out of round. In order to provide the constant bevel, the Stovall et al. machine utilizes a small arc of the pipe being cut. The arc positions the machine and changes as the cut progresses about the pipe. Stovall et al. provides means for movably engaging the end of a pipe that is being bevelled and for limiting the movement of the machine in the direction endwise of the pipe such as would move the cutter to deeper cutting engagement. Spacers movably engage the inner and outer wall of the pipe in order to position the machine laterally relative to the section of the end of the pipe that is being bevelled. One group of the spacers engages both the interior and the exterior walls of the pipe immediately adjacent the cutter while other groups of the spacers engage the inner and outer wall surfaces at points that are spaced circumferentially about the pipe.
From the foregoing, it will be appreciated that the Stovall et al. structure, while it might alter the interior dimension of a pipe if the bevel is cut deeply enough, does not provide means for removing an appreciable quantity of material from the interior wall surface in an axial direction. Furthermore, the Stovall et al. structure does not enlarge the bore of the pipe even though it does bevel the end of the pipe. It will be appreciated that even if the bevel does start from the interior surface of the pipe, the inside diameter of the pipe will always remain the same.
U.S. Pat. No. 3,141,365 granted to J. B. Peters on July 21, 1964, discloses structure that is mountable on a flanged workpiece and which provides means for centering the axis of a lathe spindle with respect to the workpiece. The Peters structure primarily provides means for refacing the flange of a workpiece such as a large diameter steam pipe. A cutting tool is provided on structure that can be moved diametrically with respect to the longitudinal axis of the pipe and circumferentially or rotationally with respect to the longitudinal axis of the pipe. It will be appreciated from a reading of the Peters patent that means are not provided for accurately removing a finite quantity of material from the interior wall of the pipe with the removed material extending for an appreciable length in the axial direction with respect to the length of the pipe.